Compressor muffler having adjustable baffle means controlled by thermally responsive element



219,141 ER HAVING ADJUSTABLE BAFFLE MEANS CONTROLLED BY THERMALLY RESPONSIVE ELEMENT Nov. 23, 1965 WILLIAMITIS COMPRESSOR MUFFL Filed Aug. 50, 1963 INVENTOR. Leo William/71's His Attorney United States Patent Ofiice 3,2 19,141 Patented Nov. 23, 1965 3,219,141 (IGMPRESSOR MUFFLER HAVENG ADEUSTARLE RAFFLE MEANS CQNTRGLLED BY THERMAL- LY RESPUNSHVE ELEMENT Leo Williamitis, @regonia, Ghio, assignor to General Motors Qorporation, Detroit, Mich, a corporation of Delaware Filed Aug. 30, 1963, Ser. No. 3tl5,7tl 4 Claims. (Cl. Isl-45) This invention relates to muffiers for compressors and the like.

One problem in suppressing fluid flow noises produced by a noise generating device such as a compressor is that of producing an economical, quickly responsive muffiling arrangement for effectively suppressing variable noise patterns generated during different phases of the operation of the compressor.

Accordingly, an object of this invention is to provide an economical noise mutfling construction capable of producing a variable noise suppressing eflect during different phases of compressor operation.

A further object of the present invention is to provide a mutfler having baffle means with an open area therethrough for suppressing acoustical disturbances caused by a first fluid flow therethrough and thermally responsive means operatively associated with the mufiier for chang ing the open area in the baffle means to suppress acoustical disturbances caused by a second flow through the muffler.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings wherein a preferred embodiment of the present invention is clearly shown.

In the drawings:

FIGURE 1 is a view in longitudinal section of the present invention;

FIGURE 2 is a View in vertical section taken along the line 22 of FIGURE 1; and

FIGURE 3 is a view in vertical section taken along the line 33 of FIGURE 1.

Referring now to the drawings, the improved mufller is illustrated as comprising a cylindrical outer casing lttl formed by cup-shaped elements l2, 14 having radially outwardly directed flanges l6, 18 respectively, secured together by suitable means such as welding. The cupshaped element 14 has an inlet opening 19 formed in the end thereof and the cup-shaped element 12 includes an outlet opening 20 therein located in axial alignment with the inlet opening 19.

Within the cup-shaped element 14, a baflle 22 is located to be directed substantially transversely thereacross. The baflle is representatively illustrated as being convexly shaped in the direction of the inlet opening 19 and as having a peripheral flange portion 24 thereon secured to the inside surface of the element 14 for holding it in place within element 14. The element 22 further includes a plurality of circumferentially located openings 26 and a single radially outwardly located opening 27 therein, as best shown in \FIGURE 2, that communicate an inlet chamber 28 formed between the baffle 22 and the closed end of the element 14 with an intermediate mufiling chamber 3% formed between the battle 22 and a like baffle 32 located within the element 12. Battle 32 extends transversely across element 12 and includes a peripheral flange portion 34 secured on the inside surface of element 12 to hold the baflle 32 in place therein. The baflle 32 is convexly shaped in the direction of the inlet 19 and also includes a plurality of circumferentially located openings 36 and a radially outwardly located opening 37 therein for communicating the intermediate chamber 39 with a discharge chamber 33 communicating with the outlet opening 2%. While two baffles are shown, a greater or lesser number may be used depending upon the muffling effect desired.

In accordance with certain of the concepts of the present invention, a dish-shaped bimetallic element 40 is operatively associated with baflle 22 for controlling fluid flow thereacross. It has a central portion thereon secured to the central portion of the batlie 22 and, when cold, is concavely shaped in the direction of the inlet opening 19, as best illustrated in FIGURE 1, so that the outer peripheral portions thereof are spaced from the upstream side of baflle 22 to form a relatively unrestricted fluid flow passageway 41 between chamber 28 and openings 26 to chamber 30. Similarly, a dish-shaped bimetallic element 42 has the central portion thereof secured to the central portion of the baflie 32 with the bimetallic 42 being concavely shaped in the direction of the baflle 22, when cold, so as to provide a substantially unrestricted fluid flow passageway 43 between chamber 30 and openings 36 to chamber 38. The illustrated bimetallic elements 40, 42 deflect toward baffles 22, 32 to restrict fluid flow thereacross and thereby serve as quick-acting temperature responsive control means for regulating the noise suppressing characteristics of the improved muffler. While dish-shaped bimetallic elements are preferred because of the ease of assembling them within the mufiler casing, it should be understood that other temperature responsive bimetallic arrangements are contemplated by the invention so long as they perform the function of producing a variable fluid flow restriction across noise suppressing baffles such as those in the illustrated arrangement.

The above-described mufller arrangement has been found to be unusually well suited for use in association with a rotary compressor of the type that discharges high pressure fluid across a reed valve discharge assembly into a cooling coil and thence to a compressor dome for discharge to a point of use. Such a compressor has two distinct fluid flow acoustical characteristics during its operation including a first acoustical phase during which the compressor discharges a relatively dense gaseous fluid at a first predetermined temperature and pressure and a second acoustical phase where it discharges a less dense gaseous fluid at a second pressure and temperature.

During the first phase of operation, it has been found that ordinary compressor mufller arrangements transmit a fluid noise that is best characterized as the hissing sound heard when a tire is being deflated. Following this initial phase of operation, the compressor generates a pulsating ping-like noise believed to be produced by the action of the reed type discharge valve on the fluid passing from the compressor. By virtue of the present invention, during the first phase of the compressor operation, which is characterized by a fluid flow temperature that conditions the bimetallic elements ill, 4-2 to be deflected away from baflles 22, 32, fluid flow passing from the compressor into the muflier through the inlet opening 19 will flow across substantially unrestricted flow areas in the baflles 22, 32 and through the outlet opening 20. Because of the substantially unrestricted fluid flow passageways in the mutter, the hissing noise generated during the first phase of the compressor operation is effectively suppressed.

Following a predetermined temperature increase in the fluid passing through the compressor, which temperature increase is a characteristic of the second phase of the compressor operation, the bimetallic elements 40, 42 deflect toward the baflles 22, 32 through an overcenter position to snap against the convexly-shaped surfaces on the baffles 22, 32 into the positions shown in broken lines in FIGURE 1 so as to block fluid flow through the openi) ings 26, 35. Hence, fluid flow through the muflier is restricted to the small area openings 27, 37 to condition the muffler to suppress the pulsating fluid flow disturbances created during the second phase of the compressor operation.

The improved muflier arrangement can thereby be characterized as an economical construction suited for mass production that has a variable noise suppressing capability in response to predetermined temperature variations in the system associated therewith. While the invention has been discussed with reference to a rotary compressor of a particlar type, it will be understood that it is equally suited for use in association with any device requiring a variable sound suppressing action during diflerent phases of operation thereof.

While the embodiment of the present invention as herein disclosed constitutes a preferred form, it is to be understood that other forms might be adopted.

What is claimed is as follows:

1. A discharge mufller for a compressor or the like comprising a cylindrical casing having an inlet opening therein and an outlet opening therein, a baifle located within said cylindrical casing having one of its surfaces convexly shaped in the direction of said inlet opening, said balfle having the outer periphery thereof in sealing engagement with the inner surface of said casing, means forming a first open area in said battle for allowing substantially unrestricted fluid flow between said inlet and said outlet for producing a first predetermined noise mufiling effect in said casing, and means including a bimetallic element located within said casing having a first portion fixedly secured to said baflie and a movable portion responsive to a predetermined temperature increase in said casing to close off a portion of said open area for producing a second predetermined noise mufliing effect in said casing.

2. In the muffler of claim 1, said bimetallic element being dish-shaped with a central portion thereon secured to said baflie on the upstream side thereof so that the curved side walls of said bimetallic element are located in spaced relationship with the convexly shaped surface of said baffle to allow substantially unrestricted fluid flow through the first open area under first predetermined operating conditions.

3. A discharge mufller for a compressor or the like comprising means forming a fluid space, means forming an inlet and an outlet communicating with said fluid space, baffle means within said fluid space for modulating fluid flow between said inlet and said outlet, said baifle means including an open area for allowing substantially unrestricted fluid flow between said inlet and said outlet to produce a first predetermined noise muffling effect in said fluid space, and thermally responsive means located within said fluid space having a first portion fixed with respect to said baflie means and a second movable portion responsive to a predetermined temperature increase in said fluid space for closing off a portion of said open area to produce a second predetermined noise mulfling effect in said fluid space, said baflle means including a plate directed transversely across said fluid space having an open area therein including a plurality of circumferentially arranged openings and an opening in said plate located radially outwardly of said circumferentially located openings, said thermally responsive means including a dishshaped bimetallic element having a central portion thereon secured centrally of said baflle and the curved side walls thereof overlying said circumferentially spaced openings in spaced relationship therewith to allow substantially unrestricted fluid flow therethrough with said curved side walls deflecting toward said plate upon the occurrence of the predetermined temperature increase to engage said plate to block fluid flow through said circumferentially located openings and restrict fluid flow across said plate through said radially outwardly located opening for producing a second predetermined noise mufliing effect in said fluid space.

4. A discharge muflier for a compressor the like comprising a cylindrical casing having an inlet opening therein and an outlet opening therein, a baflie located within said cylindrical casing between said inlet and outlet openings, said baffle having the outer periphery thereof in sealing engagement with the inner surface of said casing, means forming a first open area in said battle radially inwardly of the outer periphery thereof for allowing substantially unrestricted fluid flow between said inlet and said outlet for producing a first predetermined noise muffling eifect in said casing, a polymetallic thermally responsive element located within said casing having a first portion fixedly secured to said baflie radially inwardly of said open area and a movable portion overlying a part of said open area responsive to a predetermined temperature increase in said casing to close off a portion of said open area for producing a second predetermined noise muflling effect in said casing.

References Cited by the Examiner UNITED STATES PATENTS 1,927,947 9/1933 Newell 181-65 2,157,029 5/1939 Starkweather et al. 181-45 2,818,131 12/1957 Doughty 181-36 FOREIGN PATENTS 1,063,136 12/1953 France. 1,139,157 2/1957 France.

590,409 7/1947 Great Britain.

LEO SMILOW, Primary Examiner. 

1. A DISCHARGE MUFFLER FOR A COMPRESSOR OR THE LIKE COMPRISING A CYLINDRICAL CASING HAVING AN INLET OPENING THEREIN AND AN OUTLET OPENING THEREIN, A BAFFLE LOCATED WITHIN SAID CYLINDRICAL CASING HAVING ONE OF ITS SURFACES CONVEXLY SHAPED IN THE DIRECTION OF SAID INLET OPENING, SAID SIDE HAVING THE OUTER PERIPHERY THEREOF IN SEALING ENGAGEMENT WITH THE INNER SURFACE OF SAID CASING, MEANS FORMING A FIRST OPEN AREA IN SAID BAFFLE FOR ALLOWING SUBSTANTIALLY UNRESTRICTED FLUID FLOW BETWEEN SAID INLET AND SAID OUTLET FOR PRODUCING A FIRST PREDETERMINED NOISE MUFFLING EFFECT IN SAID CASING, AND MEANS INCLUDING A BIMETALLIC ELEMENT 